Larry Woodman reported current VM has big performance regression whenAIM7 benchmark. It use very much processes and fork/exit/page-fault frequently.(i.e. it makes serious lock contention of ptelock and anon_vma-lock.)

At 2.6.28, we removed calc_reclaim_mapped() and it made vmscan, thenvmscan always call page_referenced() although VM pressure is low.It increased lock contention more, unfortunately.